1. Field of the Invention
The present invention relates to an ink-jet recording method, an ink-jet recording apparatus, an ink tank to be removably mounted on such apparatus, and an ink-supplying means for supplying ink to the ink tank, which make possible to obtain a high-quality image on a recording medium. In addition, the present invention also relates to recording systems including a copying machine, a facsimile, and a printer, and also a word processor and a personal computer integral with a recording device, and a recorded material provided as a recording medium on which an image is recorded by the recording apparatus.
2. Related Art
Heretofore, ink-jet recording apparatuses have been used as output means on the commercial basis, for example they have been used as printers as output means of recording systems such as output devices of copying machines, facsimiles, electronic typewriters, and word processors, output terminals of work stations, and the like, and also such as handy- or portable-type printers equipped in information-processing systems such as personal computers and host computers, optical disk apparatuses, video apparatuses, and so on. In these cases, each of the ink-jet recording apparatuses is configured to meet a specific function, a usage pattern, and the like of the corresponding apparatus.
As a general ink-jet recording apparatus, it has been known that one comprises a recording device (recording head), an ink tank for storing ink to be supplied to the head, a sheet-feed device for feeding recording paper, and a control device to control these devices. The recording head that discharges ink droplets from a plurality of nozzles is serially moved or scanned in a direction (main-scanning direction) perpendicular to a direction of feed (sub-scanning direction). The ink-recording head performs a recording movement, in which the recording paper is intermittently fed a distance equal to the recorded width during non-recording intervals. In the case of a configuration of the ink-jet recording apparatus that uses an on-demand type recording head by which ink is ejected onto the recording paper according to recording signals, it has been widely used because of the advantages of low running cost and quietness. In the case of a configuration of the ink-jet recording apparatus that uses a full-line type recording head in which a plurality of nozzles for ejecting ink is arranged linearly in the sub-scanning direction, the recording head need only scan the recording paper once to perform recording of a width corresponding to the number of nozzles. This makes for increased speed of recording operation.
The supply, a supply of ink deteriorates in quality when the remaining quantity of ink in an ink storage member such as the ink tank described above is lower than a predetermined level. As a consequence, a poor printed output may be obtained and so high-quality image formation becomes difficult. If tank becomes completely empty of ink, furthermore, an image cannot be formed on the paper while ink-ejecting means of the recording head is driven in spite of the absence of ink. In this case, therefore, the possibility exists of causing the failure of a ink-ejecting means. Especially in the case of using a heater for ejecting ink, as is described later, possibility exists of destroying the whole structure of the recording head by the effect of abnormal heat-up. Conventionally, therefore, ink-jet recording apparatuses have a device for detecting the presence or absence of a liquid (hereinafter, also referred as a liquid-detecting device), as shown in FIG. 1.
The liquid-detecting device shown in FIG. 1 comprises a cylindrical rod 1001, a light source 1003 connected with the rod 1001, and a light-receiving unit (i.e., a photosensor). In this kind of the device configuration, the rod 1001 is in the type of having light transmission properties and also having a tip portion which is cut in a slanting direction. As shown in the figure, the rod 1001 is arranged in an ink tank 1002. The light source 1003 emits light toward a bottom of the ink tank 1002 through the tip portion of the rod 1001. In the case that the distance between the tip portion of the rod 1001 and the bottom of the ink tank 1002 is kept at a constant, the following conditions can be observed:                the condition that the tip portion of the rod 1001 is immersed in ink I (e.g., ink level is indicated by a solid line A higher than the tip portion);        the condition that there is a space between the tip portion of the rod 1001 and ink level (e.g., ink level is indicated by a solid line A′ lower than the tip portion); and        the condition of empty out the ink tank 1002.        
Under each of these conditions, reflected light having its own refractive index can be detected. Therefore, through the use of the differences in refractive indexes under the above conditions the presence or absence of ink can be determined by detecting whether the ink level is positioned between the tip portion of the rod 1001 and the bottom of the ink tank 1002. Thus the photosensor 1004 receives the reflected light passing through the tip portion of the rod 1001, and then the condition of the remaining quantity of the ink is determined by the control unit 1005 connected with the photosensor 1004. If the control unit 1005 makes a decision that the remaining quantity of the ink is lower than the predetermined quantity, the operator is instructed to change or fill the ink tank by means of an indicator on an operation panel (not shown) which is electrically connected to the control unit 1005.
However, in accordance with the conventional ink-detecting method described above, light emitted from the light source 1004 is reflected at an inner peripheral side wall of the rod 1001, so that it is difficult to keep a constant incidence angle of reflected light against a slant portion of the rod 1001 does not remain constant. It results in the problem that the difference between the strength of reflected light in the presence of ink and the strength of reflected light in the absence of ink cannot be broadly divided. In addition, it also results in the problem that the device configuration increases in complexity because of installing the rod 1001 in the ink tank (i.e., an ink-flow path of the ink tank). Furthermore, it is difficult to respond to consumer demands, such as for smaller and cheaper devices, to a sufficient degree because of enlarged volume and limited shape of the ink tank as a result of arranging the rod therein.